CNC machines are becoming ever more widely used for producing machined parts. As a result, numerous tools have been designed for use with CNC machines. Bar pullers are one such type of tool.
Prior art CNC machine bar pullers, such as the bar puller disclosed in United States Pat. No. 4,522,091 to Toffolon have not been easily or fully adjustable. The bar puller in Toffolon uses a pair of toothed jaws for gripping, biased by a pair of coil springs. The jaws are affixed to a rectangular head by screws. The head contains a series of threaded openings to which the jaws may be secured. The opening of the jaws is adjusted in steps by securing the jaws to different threaded openings in the rectangular head. As a result of the incremental size adjustment of the opening only bar stock of compatible sizes may be used.
There exists a need for a bar puller providing easier adjustment of the jaw opening than prior art bar pullers. Such a bar puller should be adjustable without requiring removal from the CNC machine; be continuously variable within the size range of the bar puller, provide a desired gripping force at each size adjustment; offer cross-slide and axial engagement; and have a self centering jaw opening.